14 BULLETIN 862, U. S. DEPARTMENT OF AGRICULTURE. 



nearly filled. with the small individual plants, or thalli, of a duck- 

 weed (Lemna sp.). These plants are very abundant in many of the 

 localities from which the baldpates were taken, but for some reason 

 other foods seemed to appeal to them more strongly. 



SMARTWEEDS (POLYGONACEAE), 1.47 PER CENT. 



The seeds of water smart weed (Polygonum amphibium) were pres- 

 ent in 11 baldpate gizzards, those of dock-leaved smartweed (P. 

 la path i folium) in six. Others identified were kno tweed (P. avicu- 

 lare), water pepper (P. hydropiper), and lady's-thumb (P. persicaria), 

 each in two, and mild water pepper (P. hydropiperoides) and black 

 bindweed (P. convolvulus) , each in one. The fact that the seeds of 

 smartweeds are the only edible parts of these plants probably is the 

 reason that they form so small an item of the baldpate's diet. 



ARROW-GRASS FAMILY (jUNCAGINACEAe), 0.36 PER CENT. 



The arrow-grass family was represented in two baldpate stomachs 

 from the State of Washington; both were nearly full of the seeds 

 of arrow-grass (Triglochin maritima) . These plants are quite closely 

 related to the pondweeds, but, unlike the pondweeds, their seeds 

 are the only parts eaten by birds. 



WATERLILY FAMILY (NYMPHAEACEAE), 0.26 PER CENT; AND HORNWORT FAMILY 

 (CERATOPHYLLACEAE), 0.24 PER CENT. 



One stomach from Oregon was nearly filled with 50 of the large 

 seeds of spatterdock (NympJiaea sp.J and fragments of many more. 

 Two others contained seeds of watershield (Brasenia schreberi), and 

 one the seeds of another waterlily (Castalia sp.). 



As already stated, the baldpate seems to lack the gadwall's taste 

 for the foliage of coontail (CeratopJiyllum demersum). Only one 

 bird (taken in Oregon in December) had its stomach full of this 

 plant, and two others had taken a few of the seeds. 



MISCELLANEOUS VEGETABLE FOOD, 7.63 PER CENT. 



The stomach of one baldpate from lower Chesapeake Bay con- 

 tained the remains of about 400 seeds of beggar-ticks, or "pitch- 

 forks" (Bidens srp.). In another from Texas were over 500 seeds of 

 a wild heliotrope (Hdiotropium indicum), which are often taken by 

 ducks in much smaller numbers; in this instance they furnished 80 

 per cent of the contents. A stomach from Virginia was filled with 

 the remains of ;t great many small tubers of arrowhead (Sagittaria 

 sp.); one from Massachusetts contained quantities of the leaves of 

 pipewort (Eriocaulon sp.) ; and one from Utah was from a duck which 

 had made ;i meal of the foliage and seeds of picklegrass (Salicornia 

 iinihigua). Among other items found in small quantities were bits of 

 the scales from cones of cypress (laxodium distichum) , seeds of bur 



